The invention relates to a high frequency coupling for coupling two coaxial cables, said coupling being assembled of a cylindrical housing with two open ends, whereby the respective cables in the open ends in question can be connected together in the housing by means of clamping means.
Such a high frequency coupling is generally known and is used in networks and systems for transmitting high frequency signals. More particularly data-processing systems can be considered here, such as computer and telephone networks, as well as professional high frequency systems, such as community antenna systems. In the various systems the transmission of high frequency signals usually takes place via underground coaxial cables. These may for example be of the well-known type: Sas, Sas Slimline or Bamboe. In some places these underground cables, stiff and not very easy to handle, have a fixed connection to an aboveground high frequency processing unit.
Such a fixed connection has quite a few disadvantages. Not only is the exchange of a processing unit, possibly defective or in need of replacement, made more difficult, but moreover it appears that, due to temperature and weather influences and due to subsidence of the ground, the length of the underground cable varies a few centimeters, dependent on the circumstances. In order to overcome these drawbacks the introduction of a high frequency coupling between the coaxial underground cable and a coaxial cable coming from the processing unit may be considered. In practice, however, it appears that such a high frequency coupling must meet a whole range of stiff requirements. A few instances are:
the high degree of reproducibility and constant quality required in particular of professional systems, both with regard to the electrical and with regard to the mechanical properties of the coupling. With regard to the electrical properties a good permanent connection between the respective inner and outer conductors of the coaxial cables is most important, as well as good high frequency transmission properties coupled to low frequency radiation losses over a wide frequency range to approximately 1 GHz. With regard to its mechanical properties the coupling must be made of materials which preserve their mechanical strength for a long time and under changing circumstances. In particular these materials also need to be resistant against acids, salts and moisture present in and near the ground;
furthermore it is important that the coupling can be mass produced in a simple manner at a low cost price;
it must be possible for the coupling to be provided at the work station by the average skilled worker, without any laborious activities such as soldering;
it is especially important that the coupling is resistant against extreme weather conditions and that it is furthermore unconditionally watertight for a long time under these changing circumstances; and
furthermore the coupling must meet all the requirements made by the various inspection authorities at home and abroad.